How to fix grub error after 2 disk failures in a raid1 in Debian

I was recently lucky enough to get two out of two raid1 disk failures on an important server running Debian. These two disks were the only disks in the machine. So I had to replace the two disks in a machine quickly…

I’m not sure if it was firmware or what, but these two SSDs went out at the same time. Which was lovely. One failed a bit harder than the other. I was lucky enough to be able to replace one, sync the raid, and then swap out the other. I had very little downtime and it could have gone a lot worse.

One symptom I found later while updating my system is that update-grub fails with the following error:

Generating grub.cfg ...
/usr/sbin/grub-probe: error: no such disk.

After doing a lot of digging on the net, I found out the solution to this is stupid easy. Simply reconfigure the package!

# dpkg-reconfigure grub-pc

I will admit I didn’t look into this enough to find out exactly what the problem was. I know it had to do with replacing both disks in the machine. I hope this simple solution helps someone else out there, and hopefully they won’t have to dig around for 20 minutes either.